Bending brass tube

[Bob Abell 2Participant @bobabell2]

A novel method

[Bob Abell 2Participant @bobabell2]

Hello chaps

Just been watching…."How it's made"………on tonight's TV

They were making trumpets with thin wall brass

Having rolled and soldered the main body of the trumpet, they ended up with a Post Horn shape. The next job was to bend the thin end back through 180 degrees!

This should be interesting, I said to myself

They filled the tube with water and froze it in Nitrogen!

The tube was then bent around a former, quite easily with no collapsing!

Never seen that done before!

Bob

[Colin BishopModerator @colinbishop34627]

Easy if you happen to have the frozen nitrogen I suppose….

Colin

[Bob Abell 2Participant @bobabell2]

I assume the household freezer would be suitable?

They were using Nitrogen just to speed up the freezing process….I think

Bob

[Paul TParticipant @pault84577]

Hello Bob

Many years ago I was shown how to bend copper (and brass) tube with dry sand. Cap one end, fill with dry sand and ram to compact then cap the other end.

The sand prevents the tube walls from deforming whilst being bent.

Make the bend and then remove the sand.

I can understand how the process you watched would work but I dont think that a domestic freezer could get the ice hard enough to prevent the tube from collapsing (hence the Nitrogen)

Paul

Check your messages old chum

[Bob Abell 2Participant @bobabell2]

Hello Paul

You are probably right about the freezer, but annealed 10 thou brass is very soft

They did most of the early bending round a mandrel, with just fingers alone

This reminds me of another little novelty……

When champagne is being processed, dregs form at the top of the bottle behind a temporary bung

With the super fizziness of the liquid, they have to freeze the top with Nitrogen, remove the bung, then scrape out the frozen dregs somehow and replace the stopper. Or something like this

No messages recieved in my mail box, at the moment?

Bob

[Paul TParticipant @pault84577]

Hi Bob

I have seen the same thing about champagne….how did they do it before the use of Nitrogen became available?

Sorted out the message (blame the computer)

Paul

[ashley needhamParticipant @ashleyneedham69188]

Paul, they probably didnt, and no one noticed! in any event, when opening the champas, an amount of said liquid gets expelled behind the cork, and takes the gunge with it ???

Bending small diameter brass tube is the trick….how?

Ashley

[Bob Abell 2Participant @bobabell2]

Just had a thought!

Almost a Eureka moment?

Wouldn't it be nice, if handy lengths of brass tube was sold, already filled with lead?

There yer go!……….Could be a nice little earner?

Bob

[Paul TParticipant @pault84577]

Nice idea Bob

How do you get the lead out after the tube has been bent?

Paul

[ashley needhamParticipant @ashleyneedham69188]

Would likely double the price of a bit of tube Ashley

[Bob Abell 2Participant @bobabell2]

Paul and Ash

The lead can easily be removed with a blow lamp

Paying extra would be ok, if a nice bend was essentia

Filling a tube with molten lead is not recommended for most model makers, you would need some very specialised tackle…..viz

A safe stand to hold the tube vertical, a very neat pourer, probably a fine funnel and a steady hand and good eyesight!l

Not forgetting safety goggles also.

When I was a young lad, my elder brother tried to cast a strip of lead….. In a wet clay mould!!!

It exploded and covered the kitchen ceiling and us with lead splatter! How we weren't blinded was a miracle!

Safety equipment is essential for most engineering undertakings….As most of us already know of course

Bob

[Paul TParticipant @pault84577]

Hello Captain Bob

I think the problem with the average model maker melting lead out of the brass tube is summed up in the graphic description of your kitchen experiment.

But the prospect of having such fine control over bending tube has considerable merit and is a true engineers solution , I am going to have a play with your suggestion this afternoon but instead of lead I am going to use plumbers solder simply because it has a lower melting point and should flow better.

Paul

[David Marks 2Participant @davidmarks2]

Gentlemen

Hopefully i am not informing you of something that you are already aware.

Attending the local Technical College when I was a Mechanical Engineering apprentice back in the late 1960s, we had a regular dose of Metalurgy i.e. learing about the chemical, and mechanical properties of different metals and more importantly thier appropriate use.

Woods Metal is an alloy containing Lead, Tin and Bismouth (to name jus ta few). It has an extremely low melting point andone of its uses was for a sealing plug in fire sprinkler systems i.e it melted when if got hot and in doing so actviated the sprinkler. Also you could fill a copper, brass or stainles steel tube with the molten material, allow it to solidify, bend the tube, then reheat to remove the alloy……..leaving one `formed tube'. In its latter format it was called Cerrobend (a tradename).

[Bob Abell 2Participant @bobabell2]

Hello David

That sounds just the right sort of stuff for the job!

Where can it be obtained?

Bob

[Kimosubby ShipyardsParticipant @kimosubbyshipyards]

Hi Bob and others,

cerrobend can be got here http://www.bendalloy.co.uk/page5.html

never used it but might want to, let us know if it works ok Bob.

Kimosubby

[David Marks 2Participant @davidmarks2]

Bob

Yes a quick "Google" identified Bendalloy as a UK supplier of Cerrobend. Via their STD Code., they are in Huddersfield. May be worth an email to outline what you are trying to achieve i.e. tube bore size, wall thickness, bend radius etc. and seek thier comments, advice etc.

As you will see from the information available, Cerrobend melts at around 70 Centigrade i.e. well below the boiling point of water.

Regards – David

[Paul TParticipant @pault84577]

Bob

Loading the brass tube with plumbers solder works well as I could form some very tight bends, the tube walls remain smooth with no deformation.

Good idea Bob

Paul

[Bob Abell 2Participant @bobabell2]

Many thanks to all concerned!

I was only proposing a method of bending thin brass tube, as seen on the TV prog

I haven't got a reason at the moment, for bending the stuff!

Bob

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